Direct experimental observation of topological orbital moments

Demonstrate the topological orbital moments arising from non-trivial magnetic spin textures through a direct experimental measurement, thereby distinguishing them from spin-orbit-coupling-induced orbital moments.

Background

Topological orbital moments (TOMs) are orbital magnetic moments associated with the real-space topology of non-coplanar magnetic textures, such as triple-Q states and skyrmion lattices. Unlike spin-orbit-coupling-induced orbital moments, TOMs can exist even when spin-orbit coupling is neglected and can remain finite in systems with a compensated total spin moment.

The paper notes that transport experiments in intercalated van der Waals materials provide only indirect evidence for TOMs, while a direct observation remains unavailable. Ultrathin magnetic films are proposed as candidate platforms because local techniques such as spin-polarized scanning tunneling microscopy and possibly tunneling anisotropic magnetoresistance could resolve the spatially varying orbital moments. A direct measurement would also help establish the topological origin of the observed orbital signal, which can otherwise be accompanied by spin-orbit-coupling contributions.